Abstract: A multilayer film can comprise: a plurality of layers, preferably 4 layers to 128 layers, comprising: a polymer A layer comprising a polycarbonate copolymer and a polymer B layer comprising a semi-crystalline biaxially-oriented polyester; and an inter-diffusion region between each polymer A layer and polymer B layer; wherein a differential solubility parameter of polymer A towards polymer B (??AB) is 2.6 MPa1/2???AB?3.0 MPa1/2. Each polymer B layer has a particular crystallinity. The multilayer film can exhibit a combination flexibility and impact resistance.

Abstract: A method of forming a microneedle array having alternating layers of material includes transforming a multilayer sheet by cutting, assembling and stretching steps to form a stretched, stacked multilayer sheet. The stretched, stacked multilayer sheet is cut, assembled and stretched to form a film, the film is heated, and at least a portion of the film is caused to be displaced into a plurality of recesses thereby forming a plurality of protrusions at a surface of the film.